The application of fine powdered material (usually in the range of 2-15 microns), to a ground surface or any other flat surface exhibits a property of “bridging” as the powder flows from, or exits, a container or compartment. This property of bridging disrupts the desired even distribution of the powder in many commercial applications, such as for example the application of insecticides and fungicides. Drop spreaders are typically designed for the application of more dense material such as fertilizer and seed. This renders drop spreaders ineffectual for the application of fine powders since the powder material exits a drop spreader unevenly due to bridging. An uneven distribution does not allow for a controlled and repeatable application typically desired. At worst, bridging does not permit any distribution of the powder.
Centrifugal or spinner spreaders are alternatives to drop spreaders. However, spinner spreaders also exhibit a “bridging” of powder materials as the powder exits the compartment. Spinner spreaders are generally less desirable than drop spreaders since the fine material creates harmful airborne dust, if the powder exits the compartment at all. The airborne dust from spinner spreaders can endanger the health of the operator when harmful materials are applied. Drop spreaders, on the other hand, create a minimal amount of dust. While the disadvantage of airborne dust exhibited by spinner spreaders is avoided by using a drop spreader, the “bridging” property of finely ground material makes the drop spreader an ineffective delivery method for powder material such as diatomateous earth (DE), insecticides and fungicides.
There is a need in the art for an apparatus that may be used to spread powdered materials reliably, evenly, and safely.